Hereditarian scientific fallacies.
Some have recently declared that a hereditarian or more balanced approach has triumphed over environmentalism as an explanatory tool for variation in the cognitive ability and behaviour of humans. However, the entire debate is constrained by several fallacies described here. Heritability of a trait, does not predict the effect of environmental or genetic changes on the trait (Fallacy #1), so knowing heritability does not assist in writing prescriptions for societal ills or budget cuts. Heritability estimates themselves are inaccurate, given the potential for gene-environment covariance and interaction, as well as other non-additive effects on behavior or cognitive ability (Fallacy #2). The 'revolution in molecular genetics' has provided more effective tools for describing the genome, but doesn't permit separation of gene and environmental effects on traits (Fallacy #3). If we were able to measure heritability accurately, it would give us absolutely no indication of whether or not group differences are genetically based (Fallacy #4). Finally, any proposed models of the evolutionary divergence of human groups must more adequately answer the basic questions of such a study, and are not supported by high heritability in present populations (Fallacy #5). Humans are not and should never be exposed to artificial selection and crossing experiments, so behavior geneticists will continue to be very limited in their ability to partition the effects of genes, the environment, and their covariance and interaction on human behavior and cognitive ability.
Bailey
R C
RC
Department of Zoology, University of Western Ontario, London, Canada.
D005075:Biological Evolution; D004777:Environment; D014644:Genetic Variation; D005824:Genetics, Behavioral; D005826:Genetics, Medical; D005838:Genotype; D006801:Humans; D007360:Intelligence / Q000235:genetics; D008957:Models, Genetic; D010641:Phenotype; D012641:Selection, Genetic; D014427:Twins / Q000235:genetics / Q000523:psychology